Turbine nozzle guide vane construction



Sept. 2, 1952 J. T. PURVIS 2,609,176

TURBINE NOZZLE GUIDE VANE CONSTRUCTION Filed Jan. 21, 1950 ATTORNEY Patented Sept. 2, 1952 TURBINE NOZZLE GUIDE VANE CONSTRUCTION Joseph Thompson Purvis, Toronto, Ontario, Canada, assignor to A. V. Roe Canada Limited, Malton, Ontario, Canada Application January 21, 1950, Serial No. 139,867

' This invention relates to turbines and other axial flow power conversion machines wherein the blading is subjected to a flow of'fluid at relatively high temperatures. The invention more specifi- 3 Claims. (01. 253-78) 2 7 guide vane mounting that permits the ready removal and replacement of worn or damaged parts.

A still further object of the invention is to provide a guide vane mounting arrangement concally relates to an improved mounting for tursisting of the smallest possible number of parts. bine nozzle guide vanes. Other objects and advantages will become ap- It is customary, in the mounting of turbine parent during the course of the following descripnozzle guide vanes for axial flow turbines, to setion. ,cure the said vanes by their inner platforms or In the drawings accompanying and forming a extremities to a diaphragm surrounding the tur- 10 part of this specification, in which like reference bine shaft, and to make provision for expansion characters are used to designate like parts in the attachment of the outer extremities of the throughout the several views, Fig. 1 is a fragvanes to the surrounding engine casing. Almentary perspective view of a turbine structure though this arrangement has some advantages of in which are included turbine nozzle guide vanes assembly, in that the vanes can be installed beconstructed according to the invention, as 010-- fore the outer casing is assembled, it suffers from served when viewed in a direction parallel to the the disadvantage that the engine must be very axis of the turbine and in the same sense as the extensively dismantled if it is found necessary to fluid flow; and Fig. 2 is a fragmentary sectional replace individual guide vanes which may become view taken on a radial plane through t e casing burnt or otherwise damagedin service. Furtherstructure and viewed in the direction of the armore the operating temperatures of the inner at- O in l tachment points are relatively indeterminable Referring to the drawings, a typical turbine and not readily measurable on test, whereas a comp-r s d u e Casi g Iii and a fixed inclose and accurate control can be exercised over 1181' S uctu e I l Spa d from the Said Casing and the temperatures of the engine casing and the provi i a passage f r t fl w f fl id fr m the outer attachment points of the vanes which this usual nozzle box l I rearwardly into the turbine. casing provides. Suitable means are provided to hold the casing The principal object of this invention i t proand the inner structure in spaced relationship. vide a mounting for turbine nozzle guide vanes he Words inner and outer are used herein which will enable the position of the vane nde in reference to the senses radial to the engine). operating conditions tobe predetermined with According to the invention, each of a plurality some accuracy and at the same time W111 facilitate of o le uid v s 12 t ds radially cr the replacement of vanes which become damaged an annular p c d b tween the fiXed in service. inner structure II and the fixed outer casing 10. Another object of th in entio i t provide A circumferential channel [4 is provided in the a mounting for turbine nozzle guide vanes which inner structure II, the sides of the said channel provides firm support against the loads imposed being d fi d y an a ul r flan e I5 on the inner by the working fluid and makes provision fo structure H and a flanged retaining ring l6 atrelative mov ment b tw th blading and t tached thereto. At the outer side of the annular adjacent structures caused by temperature variagap l3 there is Similarly pr vi d a circumferentions. 40 tial channel I! lying between the rear face Ill Another object of the invention is to provide e 011118! Casing and a turbine r d rin a mounting that permits each guide vane to'exsecured to the 0111591 n pand or contract independently in relation to the Each guide v n has an ou r base member or adjoining guide vanes, platform [9 and an inner base member or plat- Another object of the invention is to provide form i" which provide means for'mounfing the a guide vane mounting wherein the-loads imvanes m the channels the vanes posed by the Working fluid tend to hold the guide l 2 curve away from the axial direction at a convanes firmly against their mountings thereby slderable aligle and adJacent vanes must b I v spaced relatively closely together, the inner and helping to support the guide vanes and mimmiz- Outer vane platforms 2n and '9 r k d th t ing the leakage of working fluid through the inthe rear edge of each Vane e ewe p platform is not-1n axial terstices between the base portfons of h gulde alignment with the front edge but is displaced vanes and between the base por io and adjacent tangentially to the turbine in the direction of members. 7 curvature of the guide vanes. w

Another object of the invention is to provide a ltwhe'i'nnei' tpl tfd 2' chfd thm vanes I2 has an inwardly projecting flange 2I at the forward edge of the platform and a smaller inwardly projecting flange 22 at the rear edge of the platform. The flange 2I is provided with a radial slot 23 which engages with one of a series of evenly spaced rearwardly projecting teeth 24 carried by'ithe flangeIS on thein'n'er structure I I. The smaller-mange 2-2 on the rear edge (if inner platform is just long enough radially to make contact with the retaining ring I6 on the inner structure I I when the guide vanes are in extreme contracted position relative to the inner structure II and the outer casing II]. Sufiicient clearance for radially inward expansionof the-:guidevanes I2 is provided at the inner extremities of 'Sflanges .2I and 22.

The outer platform IQ of each-of the guide 'vanes I2 is located in channel I'I and'has a rela- 'tively small outwardly projecting flange 2-5 at.

-the forward edge of the platform and an outwardly and rearwardly projecting right-angled :flange 26 attherear-edge of the: platform. The right-angled flange 26 is provided witha:radial slot--21 engaging with oneof a series of evenly spaced forwardly-projecting teeth-28 on-the-forward-face of turbine shroud-ring I8. ii-clamping plate "29 is removably attached to-the shroudring .IB and has an annular shoulder '29 at the inward end, which receives the outermost edge of the-right-angled flange 26 oneach-of .theouter platforms I 9 andclamps thesaid flanges inpositionagainstshroud ring I'8. Thesmallei flange on-the outer-platformIQ is just long enough radially to rest against the rear face Ill of the outercasing 'I-Il when the guide-vanes I2 are'in extreme contracted positionrelative tothe inner structure. I I and the outer casing I0.

-=In thecomplete assembly, the guide vanes =I-2 are fixed with respect to-the outercasing I U by meansrofthe clamping; plate 2 9 andtheiengagement of teeth 28 with the slots 21, whilethe-vanes are'free to 'expand and contract relativetothe innerstructure II because relative radialmovement is possible between the teeth -24 and the slots'23. The axial-gas loads acting on the vanes are earned by the forward reaction of the 1 turbine shroud ring I8 against the read edges of the right-angled flanges 26" at therear-of outer platforms I9-and by the forwardreaction ofthe retaining ring l6 against theflanges-22 atthe rear of innerplatforms '20. Th-etangential-gas loads are carried by thetangential reactions of -teeth Hand-28, againstthe-sides of the radial-slots 23 and- 2'! respectively.

From the foregoing description it will be apparent that the guide vanesarei positively located with 'respect to the shroud ring I8 and the outer casing I0; and are independent of-the radial expans-ion andcontraction of zth'e inner structure I I. The -operating temperatures of the shroud ring and the outer easing are 'well understood and can -be easily-controlled by insulation and other means so that the-position of thesguide vanes under operating :conditionscan Ebe raccurately-predetermined; this is a point of some importance since the relationship betweenthe guide vanes and thei turbirre' rotor blades has amarked effect-upon theperformanee of-the engine. Moreover,-va-neswhich become damaged-inservice can be readily replaced by the removal of the shroud ring I8 and the clamping. plate 29,-'e nabling-"the damaged'vanesto be wi-thdrawn-fromthein inner mountingswithout-theznecessity of removing-the turbine-rotor-and other major; dismantling' operations. (It is, of course, important=-that--the mine -.-should v-be mounted with its longitu'dinal axis in a vertical position during this operation, so that the vanes will rest on their flanges 25; otherwise many of them will fall out when the clamping plate is removed.)

Thermal insulating material may be placed in the channels I4 and H, in order to prevent excessive loss'ofhea't fromthejguideivanes and also to prevent the damage to other which escaping heat might cause.

It is to be understood that the form of the invention herewith shown and described is to be takentas'apreferred example of the same and "that "various changes in shape, size and arrangement: of theiparts'may be resorted to without departing from-*thespirit of the invention or the s'cope' of the claims.

surf-ace provided with a series-of'circumferen tially spaced surface interruptionshaving radially and axially disposed faces, said inner structure having a radially protruding annular ,surface downstream of the said first-mentioned surface and facing upstream of the flow, a p1ur a1ity X of, guide' vanes traversing the-annular passage, each of the guide vanes having an outer yplatform adjacentthe outer casing and aninner platform adj-acent the inner structure, clamping :means on the outer casing securing the-outer platformsto the outer casing eachofthe guide-vanefillmr platforms having at its upstream side a radially inwardly extending projection, the :projections being ;in radially and axially slidable engagement 'with the Einterruptio'ns on :the;said firstmentione'd surface to permit radial and downstream axial movement and to prevent-circum-' ferential1movement of the guide vanes with respect to the inner structure, the downstream side of: each of the guidevane innerr'platforms a abutting the-said protruding 'annular surface to permit'relative radial and circumferentiallmovement but to prevent downstream axial move-'- ment of the-.g-ui'de-vianes with respect to the inner structure.

2. In an-axial flow elastic fiui'dipower conversion machine, a'fixed-annular outer casing,'-ia fixed'generally cylindrical inneristructure -within andradially spaced from 'the casing' and defining therewith an annular passage for the 'flo'w of fluid' -the inner structurehavinga circumferential channel, the channel having upstream and downstream mutually facing annular side wall surfaces, the said upstream surface being ;provided with a series of circumferentially spaced teeth projecting axially from the said surface and having radially and axially disposed facesja plurality- 0f guide vanes traversing? the annular passage," each of theguidevanes having an -outer platform adjacent the outer casing and an inner platform adjacent the inner structure, I m-cans on theouter casing 'securing the outer platforms to the outer cas-ing,--'-each oftheguide vane inner platforms -having atits upstrear'n side radially 'inwardiy extending projection, ithe proiectiohs being 11in fradially rand axially slidable engagement 'with thei-tee'th to; permit": radial and. down-l streamsaxial movement 1 and:.torprevent :cir'c'umferential movement of "the: guide varies; with 1TB- spect to the inner structure, the downstreamwsidc of each of the ;guide wane inner platforms abutting the said downstream annular surface JOSEPH THOMPSON PURVIS.

6 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 973,472 Broadbent Oct. 25, 1910 1,061,675 Junggren May 13, 1913 2,013,512 Birmann Sept. 3, 1935 2,427,244 Warner Sept. 9, 1947 2,488,867 Judson Nov. 22, 1949 2,488,875 Morley Nov. 22, 1949 2,494,821 Lombard Jan. 17, 1950 FOREIGN PATENTS Number Country Date 107,788 Sweden June 29, 1943 

